Defined padding level for nested nodes.

<div class="definition">
    Number, default = 12
</div>

This property defined padding for nested nodes.
<div style="height: 10px"></div>

You can defined it during object creation:
<textarea class="javascript">
let sidebar = new w2sidebar({
    name: 'sidebar',
    levelPadding: 5,
    nodes: [
        { id: 'id-1', text: 'Level 1', hidden: true },
        { id: 'id-2', text: 'Level 2', expanded: true, nodes: [
            { id: 'id-2-1', text: 'Level 2.1' },
            { id: 'id-2-2', text: 'Level 2.2' }
        ]},
        { id: 'id-3', text: 'Level 3' }
    ]
});
</textarea>

Or any time after the object has been created:

<textarea class="javascript">
w2ui.sidebar.levelPadding = 20
w2ui.sidebar.refresh()
</textarea>